For the last 2 days I have been trying to send an email to Metlink, but they are returned with the message "Could not be delivered because of 550 5.7.1 Unable to relay The following recipients were affected: info@metlink.org.nz".

This is the address on their web site.

Thinking it may be that Metlink don't like Telstra/Clear/vVdafone, I tried sending it from both my Gmail account, and an overseas SMTP service ... all bounced with same message.

No other emails are affected.

Does this mean that Metlink's mail server/s are actually rejecting any mail sent to them? Weird